Jack Sock has told how three of the world’s finest tennis players were left standing outside a London hotel at 4am after a fire alarm went off on Tuesday morning.

Sock, Rafael Nadal and Dominic Thiem – the world numbers nine, one and four respectively – were all made to exit the building in the middle of a week when they are competing at the end-of-season ATP Finals.

Nadal had withdrawn due to injury late on Monday night and Thiem’s next match is not until Wednesday, but America’s Sock had to overcome the disruption before beating Marin Cilic later in the afternoon.

“It was probably one of the most annoying noises I’ve ever heard in my entire life,” Sock said.

“At first I didn’t know if it was a test or whatever. Then I realised it was 4am so I hoped it wasn’t just a test from the hotel.

“I went outside, saw Rafa, saw Dominic, everyone was all bundled up, freezing cold, just wanting to get back inside.

“Everyone obviously put on clothes – it was pretty cold outside – some more than others.

“I probably waited in the room for five to seven minutes, then was probably outside for another five to seven. The whole thing was probably 15 minutes of freezing, miserableness.”

Sock showed little sign of fatigue against Cilic and, as well as claiming his own debut victory at London’s O2 Arena, he became the first American to triumph at the ATP Finals since Andy Roddick in 2007.

Cilic had thrown away a break in the decider to lose against Alexander Zverev on Sunday and he managed the same again as Sock fought back to win 5-7 6-2 7-6 (7/4).

The 25-year-old may still have to beat Zverev in his final group match to qualify, with the talented German going up against favourite Roger Federer in the evening match on Tuesday.

Cilic will play his last round-robin match against Federer, to whom he lost in the Wimbledon final earlier this year. The Croatian, who led Sock 3-0 in the decider, stands on the brink of elimination.

“It is frustrating, absolutely, at the beginning of the third set I played well,” Cilic said.

“It’s definitely disappointing in both matches in that third set after being in a good position and putting myself in a good position. But unfortunately I didn’t close it.”